Form 5472

Form 5472 reports transactions between a US company and a foreign person who owns 25% or more of it: money the owner put in, money the company paid out, and payments between them. A foreign-owned single-member LLC files it with a pro forma Form 1120, by 15 April for a calendar-year company, even in a year with no income.

The penalty for not filing, or filing late, is $25,000 per form. If the failure continues more than 90 days after the IRS gives notice, another $25,000 is added for every 30 days. It's the filing foreign owners most often miss, and it's on the compliance calendar on every plan.